| This project was focused on studying and examining changes of several histocytology,antioxidant enzyme activity and poly amine oxidase activity,endogenous hormone,glucose metabolism related enzymes and metabolites,gene expression in embryonic callus of litchi cultivar ’Dadingxiang’(DDXTD)and’Xinqiumili’(XQTD),inoculated on TD medium(MS + 0.1 mg/L NAA + 0.5 mg/L TDZ + 0.1 g/L inositol + 0.4 g/L LH + 100 ml/L coconut juice + 60 g/L sucrose+10 g/L agar),and the embryonic callus of ’Xinqiumili’(XQTX),inoculated on TX medium(MS + 0.1 mg/L NAA + 5 mg/L ZT + 0.1 g/L inositol + 0.4 g/L LH + 100 ml/L coconut juice + 60 g/L sucrose + 10 g/L agar),during their somatic embryogenesis induced on different induction medium.The main results of the study were as following:1.XQTD became brown at 6th day after the inoculation(DAI).Globular bulges were observed at 9 DAI,and globular embryo structures were observed in paraffin sections.Different somatic embryos such as globular embryo,heart-shaped embryo and torpedo-shaped embryo were observed at 12-21 DAI.DDXTD was brown at 9 DAI.A small amount of globular embryos and heart-shaped embryos could be seen in paraffin sections at 15-21 DAI.XQTX were observed in globular embryos with intact primary cambium at 12 DAI,and cotyledon embryos were observed in paraffin sections at 21 DAI.In the course of somatic embryogenesis,two sources of internal and external origins were observed in the two litchi cultivars.Somatic embryogenesis was a single cell origin,and it had similar developmental processes,such as globular embryo,heart-shaped embryo,torpedo shaped embryo and cotyledon embryo.2.There was one peak in variations curve of the soluble protein content in XQTX,XQTD and DDXTD with the peak occurring at the 6 DAI,but the content of soluble proteins in XQTD and XQTX showed a slight increase from 9 DAI to 12 DAI,and DDXTD had no such changes.The malondialdehyde(MDA)content,the superoxide dismutase(SOD)activity and the catalase(CAT)activity in XQTX,XQTD and DDXTD had gentle variations and little differences.The peroxidase(POD)activities in XQTD,XQTX and DDXTD were all decreased after increases.The peroxidase(POD)activity in DDXTD was higher than that in XQTD and XQTX from 6 DAI to 18 DAI.Yet the polyamine oxidase(PAO)activities in XQTD,XQTX and DDXTD were all increased after a decrease.PAO activity in XQTD was higher than that in XQTX from 6 DAI to 15 DAI,and than that in DDXTD from 0 DAI to 15 DAI.3.The auxin(IAA)contents in XQTD,XQTX and DDXTD were all decreased after increases,IAA contents in DDXTD were higher both than these in XQTD and in XQTX from 6 DAI to 18 DAI,XQTD and DDXTD with the peak occurring at the 6 DAI,and XQTX with the peak occurring at the 12 DAI.The kinetin(KT)contents in both XQTD and XQTX were all no changes basically,and the KT content in DDXTD had a slight increase,and the KT content in DDXTD was higher than these in XQTD and in XQTX.The zeatin(ZT)content in XQTX and DDXTD also all had no changes basically,the ZT content in XQTX was decreased after an increase,and higher than that in XQTD from 6 DAI to 9 DAI,but the KT and ZT contents in XQTD,XQTX and DDXTD all were lower from 12 DAI to 18 DAI,but the lowest was in DDXTD.The salicylic acid(SA)content in XQTD and XQTD were all decreased after an increase,and the SA content in DDXTD was slightly increased.The SA contents in XQTD,XQTX and DDXTD were all low from 0 DAI to 12 DAI,yet there was one peak in the variation curve of the SA content in XQTD at 15 DAI,and the SA content in XQTD was higher than these in DDXTD and in XQTX,the SA content in XQTX and DDXTD all were lower from 15 DAI to 18 DAI.The gibberellin(GA3)content in XQTD and DDXTD all were decrease,the GA3 content in XQTX was increased after a decrease,but the GA3 content in XQTX was lower compared to the values in XQTD from 6 DAI to 15 DAI and at the 18 DAI.The GA3 content in DDXTD was higher than that in XQTD at 0 DAI,and the GA3 content in XQTD and DDXTD were similar from 6 DAI to 18 DAI.The ethylene emission in XQTX,XQTD and DDXTD had gentle variations and keep at a low level.4.The starch content in XQTD and XQTX were all decreased.The starch content in XQTD was higher than that in XQTX from 6 DAI to 15 DAI,but in XQTX the starch content was increased and higher than that in XQTD at the 18 DAI.The starch content in DDXTD was increased after decrease,and decreased again.The starch content in DDXTD was higher than that in XQTD from 9 DAI to 18 DAI.The sucrose content in XQTD and XQTX were all decreased after an increase,XQTD and XQTX with the peak occurring at the 6 DAI,but in XQTX the value was higher than that in XQTD.Also,the sucrose content in DDXTD was decreased after an increase,and then increased again.The sucrose content in DDXTD was lower than that in XQTD from 6 DAI to 12 DAI.The glucose content and the fructose content in XQTX,XQTD and DDXTD were all increased,and the glucose content and the fructose content in XQTX and XQTD were basically equal.The glucose content and the fructose content in XQTD were higher than that in XQTX at the 18 DAI,and the glucose content and the fructose content in DDXTD were higher than that in XQTD from 0 DAI to 15 DAI.5.The neutral invertase(NI)activity in XQTD and DDXTD were all decreased,the NI activity in XQTX was decreased after an increase,and the NI activity in XQTD was lower than that in DDXTD and XQTX from 6 DAI to 18 DAI.The acid invertase(AI)activity in XQTD was increased,the AI activity in DDXTD was increased after a decrease.The AI activity in XQTX was also decreased,but the AI activity in XQTX was higher than that in XQTX and DDXTD from 9 DAI to 18 DAI.The AI gene and the NI gene in XQTD,XQTX and DDXTD had similar expressional patterns,the AI gene and the NI gene in XQTD and XQTX were all decreased after an increase.The AI gene and the NI gene in DDXTD were increased,but there was a positive correlation with the activity of NI,but no positive correlation was found in the AI activities.The sucrose synthase(SS)activity in XQTX,XQTD and DDXTD all were decreased after increase,but the SS activity in XQTX and DDXTD had a slight increase from 12 DAI to 15 DAI,and the SS activity in XQTD was higher than these in XQTX and DDXTD from 6 DAI to 18 DAI.The SS gene in XQTD and DDXTD had a different expressional pattern,and the SS gene in XQTD and DDXTD had similar expressional patterns.There was no positive correlation with the activity of SS in XQTD and DDXTD,but in XQTX there was a positive correlation in SS activity.The P-amylase activity in XQTX,XQTD and DDXTD were all decreased after increases,the β-amylase activity and total amylase activity had gentle variations.The highest β-amylase activity was in XQTX,the middle level was in XQTD and the lowest was in DDXTD.The a-amylase activities in XQTX and XQTD were all increased,and the a-amylase activity in DDXTD was increased after decrease,and decrease again.The a-amylase genes in XQTX,XQTD and DDXTD were all high at Prophase,and then lower at late stage.The β-amylase genes in XQTD and DDXTD were low at Prophase,and high at late stage,but in XQTX the β-amylase genes were still high at Prophase,and lower at late stage.The p-amylase gene in DDXTD was higher than that in XQTD at 18 DAI.There was no positive correlation with the activity of a-amylase and β-amylase,and the β-amylase activity was more related to the total amylase activity.In summary,this experiments observed the difference in the somatic embryogenesis of ’Xinqiumili’ and ’Dadingxiang’,and somatic embryogenesis was a single cell origin.High POD activity and high content of IAA,KT and GA3 are more conducive to the proliferation of embryogenic callus,and in the culture,high PAO activity and high content of ZT and SA are beneficial to the occurrence of somatic embryogenesis.Glucose metabolism is closely related to somatic embryogenesis.In the culture,high sucrose content and low starch content at later stages are beneficial to somatic embryogenesis.Changes in the contents of these glucose components are related to the activities of sucrose invertase,sucrose synthase,and amylase,But the correlation of the gene encoded these enzymes is not strong,and the specific reasons need further study. |
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